Process of and apparatus for manufacturing alkali metals



No. 623,69I. Patented Apr. 25, I899.

. c. E. ACKEB. I 4 PROCESS 0F AND APPARATUS FOR MANUFACTURING ALKALI METALS.

(Application filed Mar. 6, 1898.)

2 Sheeis-Sheot I.

(No Model.)

INVENTOR M? HKATTORNEY WITNESSES:

THE NpRmS PETERS ca, wmouma. WASHINGTON, u, c.

N0. 623,69l. Patented Apr. 25, I899.

' 4 I c. E. ACKER. 4 PROCESS OF AND APPARATUS FOR MANUFACTURING ALKALI METALS.

(Application filed Mar. 5, 1898.)

2 Sheets-Sheet 2.

No Model.)

WITNESSES:

H IS ATTORNEY.

lJNTTEE STATES PATENT UEETQE.

CHARLES ERNEST AOKER, OF EAST ORANGE, NElV JERSEY.

PROCESS F AND APPARATUS FOR MANUFACTURING ALKALI METALS.

SPECIFICATION forming part of Letters Patent No. 623,691, dated April 25, 1899.

Application filed March 5, 1898- Serial No. 672,723. (No model.)

To all whom it may concern:

Be it known that LGHARLEs ERNEST AOKER,

a citizen of the United States, residing in East Orange, in the county of Essex, State of New Jersey, have invented a new and useful Improvement in Electrolysis, of which the following is a specification.

My invention consists of an improved process and apparatus for the manufacture of sodium and potassium.

Briefly stated, the process consists in forming electrolytically an alloy of some heavy metal, such as lead,with sodium or potassium, and. then distilling the latter.

In the accompanying drawings Ihave shown one form of electrolytic furnace which may be used in carrying out my process.

Figure 1 is a vertical section. Fig. 2 is a section at the plane indicated by 0 Of, Fig. 1. Fig. 3 is an enlarged detail View of the screw in elevation; and Fig. 4 is a plan View of the screw, partly in section, on the same scale as Fig. 3.

Similar letters of reference refer to corresponding parts in the several views of the drawings.

K is a cast-iron hearth supporting by suitable lugs the cast-iron pan or partition Land wrought-iron cylindrical chamber G. Upon the rim of the hearth is the magnesia lining Y, and surrounding the chamber is a magnesia-cylinder H. A tile cover rests on the magnesia-cylinder H and on the lining and is provided with openings for a suitable number of anodes, as at R, and openings for feeding salt, as at V, side walls J being provided on the salt-receptacle. Through the center of the hearth a tube 0 projects upwardly to a point above the intended level of alloy in the chamber, and surrounding this tube in the furnace is an inverted cup 4, carrying at the bottom a screw M, the blades of which are designed to force the liquid outwardly and away from the axis. The cup, with the screw, is mounted rigidly on the shaft N, supported and having its bearings below the f urnace. Suitable pipes for feeding lead, collecting the products, &c., are provided, as described later, and the whole is suitably incased in brickwork or equivalent heat-insulating material.

In starting the furnace suflicient molten lead is run in to seal the chamber G and cover the pan or partition D. The anodes having been previously placed in position with one of them lowered into the molten lead the full current is turned on, passing down through the one anode, through the lead, to the exterior of the furnace by any suitable connection, as at Z, or at X when sodium is being produced. Dry salt is quickly fed in ontop of the lead and around the anodes. The anode carrying the full current is then raised slightly above the'lead, as indicated by the voltmeter, thereby forming an arc. The surrounding salt quickly melts and thereafter conducts the .current. The melt soon extends to the anodes on either side until the entire charge is fluid and the furnace works steadily at nearly the normal voltage. The salt is decomposed by the current, chlorin being liberated at the anodes and passing off through channel and pipe U to the point where it is utilized. The sodium is liberated at the oathode-surface, where it forms an alloy. The screw M is set in motion and by a comparatively slow but positive action pulls the surface alloy continuously down between the pan or partition and chamber, when the lighter portion rises to the surface in the chamber and the heavier alloy sinks andfollows the pull of the screw and passes up under the pan or partition to the surface, where it comes in contact with the molten electrolyte, becomes the true cathode, and takes up the liberated sodium as it passes over the pan toward the chamber. The screw is turned fast enough to produce a definite movement toward and into the chamber of the shallow body of alloy in contact with the electrolyte. The forced circulation of this surface alloy continuously removes that part which is richest in sodium away from the molten salt. Salt is fed at regular intervals until the desired working depth is obtained and to replace that decomposed. Thealloybecomingricherandlighter and more bulky rises in the chamber to a height dependent on the height of the column of salt outside and the relative specific gravity of the alloy and the salt. An overflowpipe which projects upwardly in the chamber to a point previously determined, or which runs from the exterior of the furnace thereto, may be used whenever the alloy is to be re moved bodily. Down it the alloy will overflow almost continuously of nearly uniform richness, provided appropriate charges of lead and salt are fed at frequent and regular intervals. Lead is introduced in small charges, either in the molten state or in pigs of uniform weight, at definite intervals into the pipe S, which is sufficiently close to the highly-heated interior of the furnace to insure the fluidity of its contents. The charge therefore enters the furnace from below, the oxid and scum remaining on the surface in the feed-pipe. The salt is heaped up on top of the furnace and surrounding the anodes to a considerable depth, and thus serves to keep in the heat, to effect a packing around the anodes by bridging over the small annular spaces surrounding them where they pass through the cover, and to utilize what heat would otherwise be lost to thoroughly dry and heat the salt before it is introduced into the furnace. I consider this utilization of the salt for the purposes specified as being of great value, dispensing as it does with packings, lutes, dsc, besides conserving the heat of the furnace. After the furnace has been in operation for several hours and the walls have become thoroughly heated it will thenceforth work at maximum economy and the voltmeter-needle will remain stationary as long as the proper operating conditions are fulfilled.

I am unwilling to be confined to the details of thefurnac-e which I have illustrated. Various arrangements of parts other than those illustrated may be used without departing from the essential principle of operation described in the specification-namely, the removal of the lighter and richer alloy from the cathode-surface into a chamber where it is no longer in contact with the molten electrolyte. The object is when producing alloy only to work at the lowest temperature consistent with proper fluidity of the bath; but I have found when making particularly rich alloy with the furnace working at approximately the correct temperature or slightly higher that the space above the alloy in the chamber is frequently filled with the purple or violet vapor of sodium, which maybe easily observed by placing a small mirror at the bottom of pipe P. The sodium thus vaporized may be condensed and separately collected by providing the vapor-pipe C, leading from the top' of the chamber laterally and downwardly, connecting with a vertical pipe D, having a receptacle F at the bottom. The sodium vapor rises in pipe 0 above the chamber, condenses in the lateral arm, flows down to the end thereof, and drops into the receptacle F. The vaporization is facilitated by the continuous circulation in the direction of the escaping vapor of the nitrogen contained in the pipes and above the alloy, (air deprived of oxygen by sodium.) This circulation is accomplished by connecting the pipes D and P near the bottom by pipe E. Owing to the difference in temperature of the two vertical legs of the system the nitrogen rises through the chamber and carries the sodium vapor along with it, then descends through D, losing some of its heat before entering P. Since one of the causes influencing the rapidity of vaporization is the removal of the vapor from the surrounding space, it is obvious that the continuous circulation of the same volume of nitrogen is a material aid in the continuous production of sodium.

The production of sodium, as considered in the foregoing method, is more or less incidental to the production of alloythat is, the rate of distillation may be less than the rate of separation from the salt and alloying with the lead, the excess of sodium remaining in the alloy, which continues to overflow into receptacle Q. If, however, the whole temperature of the furnace be raised by working the furnace at a higher voltage, the rate of distillation approaches and equals the rate of separation, and it becomes purely a sodiumfurnace. The heat necessary to vaporize the sodium is of course conducted from the electrolyte. The same result may be accomplished without working the bath at this elevated temperature by generating heat locally in the chamber at and near the exposed surface of the alloy. I have successfully used for this purpose one or more heating-tubes, as at A B, where B is an iron tube closed at the bottom, so as to exclude alloy, and containing a small quantity of lead which effects electrical contact with a centrally-located carbon or metal resistance A, which is insulated from the walls of the tube. The upper end of this resistance constitutes the negative terminal of the furnace. The cross-section of the resistance is so proportioned to the current employed that the tubes are brought to a high temperature. This heat is communicated directly to the alloy near its free surface, where the lighter and richer alloy accumulates and where it is comparatively quiescent-2'. 9., removed from the direct action of the screw.

What I claim as new, and desire to secure by Letters Patent, is

1. The process of reducing metals from their fused salts, which consists in subjecting the salts to the electrolytic action of an electric current in the presence of a molten metallic cathode with which the liberated metal is adapted to form an alloy, in impartin g a forced circulation to the molten metal to conduct the alloy as formed to a separate chamber where it is permitted to stratify, and then volatilizing in an inert atmosphere in said chamber the metal thus liberated from its salt from an exposed surface of said cathode out of contact with the electrolyte, and collecting the volatilized metal, substantially as specified.

2. The process of reducing metals from their salts, consisting in subjecting the fused salts to the electrolytic action of an electric current in the presence of a molten metallic cathode electronegative to the metal to be reduced, and with which the metal to be reduced is adapted to form an alloy, then volatilizing in an inert atmosphere in a separate chamber the metal thus liberated from its salt from an exposed surface of said cathode out of contact with the electrolyte, and assisting in carrying off the volatilized metal by repeatedly circulating; the same body of inert gas through said chamber, substantially as described.

3. In an apparatus for reducing metals from their fused salts, a chamber in which salts are to be treated, means for electrolytically treating said salts in the presence of a molten metallic cathode with which the liberated metal is adapted to form an alloy, means for circulating the molten metal in a shallow stream past an anode or an odes into a separate chamber said chamber having a non-oxidizing atmosphere, means for withdrawing molten metal from the lower portion of said separate chamber and for again causing it to circulate in a shallow stream past an anode or anodes,

means in said separate chamber for volatilizing the metal thus liberated, and means for collecting the volatilized metal, substantially as specified.

4. In an apparatus for reducing metals from their fused salts, a chamber in which salts are to be treated, means for electrolytically treating the saidsalts in the presence of a molten metallic cathode with which the liberated metal is adapted to form an alloy, means for circulating the molten metal to conduct away the alloy as formed, a separate chamber for receiving said alloy, means for volatilizing the metal thus liberated, and means for repeatedly circulating the same body of inert gas through the said separate chamber to facilitate the removal of the Volatilized metal, substantially as specified.

In testimony whereof I have signed my name to this specification in the presence of 

